We plant the first week of October. The reason is simple. Deer tend not to use really food plots much until the acorns and other mast crop are gone. If you plant too early, by the time the deer really start using the plots, the plants are too mature and tough. If you wait until October, then the plants are still young and tender when the deer start looking for secondary food sources, and the deer seem to spend more time in the food plots.
Different strokes for different folks...that's just the way it seems to me and the way I do it. YMMV.
NRA Life Member, GCO Member, GSSF Member, NRA Certified Rifle Instructor and, oddly enough, Member Revolutionary War Veterans Association (I look a lot younger).